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This is the first report of a Si/SiGe resonant inter-band tunneling diodes (RITDs) on silicon substrates grown by the chemical vapor deposition process. The nominal RITD structure forms two quantum wells created by sharp 5-doping planes which provide for a resonant tunneling condition through the intrinsic spacer. The vapor phase doping technique was used to achieve abrupt degenerate doping profiles at higher substrate temperatures than previous reports using low-temperature molecular beam epitaxy, and postgrowth annealing experiments are suggestive that fewer point defects are incorporated, as a result. The as-grown RITD samples without postgrowth thermal annealing show negative differential resistance with a recorded peak-to-valley current ratio up to 1.85 with a corresponding peak current density of 0.1 kA/cm2 at room temperature. [ABSTRACT FROM AUTHOR]

We have investigated Sn precipitation and strain relaxation behaviors in the growth of Ge1-xSnx layers on virtual Ge substrates (v-Ge) for strain engineering of Ge. By varying misfit strain at Ge1-xSnx/v-Ge and Ge1-ySny/Ge1-xSnx interfaces, we found that a critical misfit strain controls the onset of Sn precipitation at a given thickness of the Ge1-xSnx layer. A compositionally step-graded method, in which the critical misfit strain is taken into account, was applied to the growth of strain-relaxed Ge1-xSnx layers on v-Ge. Postdeposition annealing at each growth step led to lateral propagation of threading dislocations preexisting in the layer and originating from v-Ge, which resulted in high degree of strain relaxation. An epitaxial Ge layer was grown on the strain-relaxed Ge1-xSnx layer and an in-plane tensile strain of 0.68% was achieved. [ABSTRACT FROM AUTHOR]

Abstract: We have demonstrated the formation of Ni(Ge1− y Sn y ) layers on Ge1− x Sn x layers by using solid-phase reaction for samples with Sn contents ranging from 2.0% to 6.5%. We have also investigated solid-phase reaction products in Ni/Ge1− x Sn x /Ge samples after annealing and the crystalline properties of nickel–tin–germanide layer/Ge1− x Sn x contact structures. After annealing at temperatures ranging from 350 to 550°C, the formation of polycrystalline Ni(Ge1− y Sn y ) layers has been observed on epitaxial Ge1− x Sn x layers with Sn contents ranging from 2.0% to 6.5%. We also observed anisotropic crystal deformation of NiGe with the incorporation of Sn atoms into substitutional sites in NiGe. In the case of the Ni/Ge1− x Sn x /Ge sample with a Sn content of 3.6%, the formation of an epitaxial Ni2(Ge1− z Sn z ) layer on the Ge1− x Sn x layer was found. The formation of β-Sn crystallites was observed after annealing at above 450°C in samples with a high Sn content of 6.5%. This β-Sn formation is due to the precipitation of Sn atoms. In all samples annealed at 350°C, the morphology of Ni–Ge–Sn layers is smooth and uniform. However, the surface roughness and interface roughness increase for an annealing temperature of 550°C. In particular, in the sample with a Sn content of 6.5%, the temperature at which agglomeration noticeably occurs is as low as 450°C. [Copyright &y& Elsevier]